The invention concerns a chair designed to take on variable pitches or attitudes under the push exerted on the seat and on the backrest by the seated person.
The market offers several types of chairs that have a variable pitch obtained by exploiting the flexing deformability of the structure making up the seat or backrest, or otherwise in some cases, fitting flexible parts between the structural components of the chair itself.
The pressure that the seated person exerts on the seat or on the backrest, or on both together, modifies the pitch of the chair permitting change of the seating position as desired.
It is common knowledge that by frequently changing from a leaning forward position to stretching backwards, the user tends to rub against the surface of the seat with inevitable inconveniences and discomfort.
What""s more, the most natural positions that the user tends to assume are often limited by the sole intrinsic flexing deformability of the components that make up the chair without any possibility of adjustment.
With the scope of eliminating these inconveniences, the same applicant filed an Italian patent application published with reference number V197AOOO183 and granted as IT01296682, which describes a chair with variable pitch that allows the seated person to change from a leaning forward position to more or less stretching backwards by simply pushing on the seat or on the backrest or both together, without having to rub on the surface of the seat.
What""s more, the range in variation of pitch can be modified by regulating special adjustments.
However, even the chair with variable pitch described in the aforementioned patent has the inconvenience of only permitting the seat to perform forward or backward linear movements.
The present invention intends to overcome the aforementioned limitation.
The scope of this invention is to produce a chair with variable pitch that allows greater degrees of freedom in the seat""s movement.
Such scope is achieved by producing a chair with variable pitch that has a frame set to rest on the floor; at least one central element that creates a substantially horizontal longitudinal axis X, supported by the frame; a seat supported by the central element; one pair of first stiles parallel to each other and set at the ends of the central element; and a backrest that has its top connected to each of the first stiles through first flexible couplings and its bottom connected to the seat through at least one second flexible coupling, it is characterised in that the seat is connected to the central element through swivel means designed to allow a planar rotary transverse movement of the seat combined with a rotary rocking movement of the backrest around a longitudinal axis created by the first flexible couplings.
According to a preferred form of execution the frame is made up of one pair of front legs connected to the ends of the central element as a continuation of the first stiles, and at least one pair of back legs parallel to each other and also each being connected to one of the ends of the same central element.
According to a variant in execution the frame has a single, substantially upright supporting body that has its top connected to the central element and its bottom provided with a floor standing structure.
According to both of the forms of execution, each of the swivel means that allow a rotary-transverse movement of the seat include a first swivel element fixed to the seat and a second swivel element that slides over the central element along the latter""s longitudinal axis. The swivel elements are connected together through flexible couplings and have contact surfaces that touch together.
By a combination of the reciprocal sliding movement of the contact surfaces over each other in combination with the longitudinal movement of the swivel elements around the central element, a planar rotary-transverse movement of the seat is generated parallel to the level on which the seat rests when in its idle position.